1. Field of the Invention
The present invention relates to Internet Quality of Service (QoS) technology. More particularly, the present invention pertains to a method and apparatus for characterizing required network resources during transmission of network traffic.
2. Related Art
Real-time media such as video and audio are often delivered over a network such as the Internet to enhance the contents of a wide variety of data. Appropriate network resource reservation and management is crucial both for the timely delivery of the traffic corresponding to these real-time media and to ensure efficient use of limited network resources. A number of methods have been proposed by organizations, such as the Internet Engineering Task Force (IETF), to provide a QoS guarantee for real-time traffic. The most prominent method for providing QoS is Resource Reservation Protocol (RSVP) (Braden, R., Zhang, L., Berson, S., Herzog, S., and Jamin, S., xe2x80x9cRSVPxe2x80x94Version 1 Functional Specificationxe2x80x9d, September 1997). RSVP employs a parameter known as the traffic specification (TSpec) to reserve network resources for transmitting the real-time traffic. TSpec is based on the token bucket model and is a standard parameter for characterizing a pattern. Specifically, TSpec is based on several values including the value r which is related to the average bandwidth (e. g., bytes per second) of the traffic and the value b which is an indication of how xe2x80x9cburstyxe2x80x9d the traffic is (e. g., fluctuations in bandwidth above and below the value for r).
RSVP requires the end-hosts to submit a request for the reservation of network resources. The network responds to the host by confirming whether or not the requested network resources have been successfully reserved. To accurately request the network resources required to deliver the real-time traffic pattern, the host must first characterize the traffic. For audio/video application developers and Internet users, pre-specifying traffic characteristics for each codec (coder/decoder) is a difficult task. The characteristics for well known audio/video codecs, such as H. 261 (International Telecommunication Unionxe2x80x94Telecommunications Standardization Sector (ITU-T), March, 1993), and H. 263 (ITU-T, Dec. 5, 1995) can be roughly estimated. However, network traffic is highly dependent on such variables as the frame rate, the resolution, and the scene complexity. Additionally, silence suppression or interframe coding techniques, may result in varying bit rates.
In some systems, such as those with WinSock2 (Windows(copyright) Socket Version 2; an add on feature of Windows(copyright) 95 Operating System and installed in Windows(copyright) NT Operating System, Version 4 and later and Windows(copyright) 98 Operating System (Microsoft Corporation, Redmond, Wash.)), TSpec templates for a few well known codecs are accessible. This situation creates many disadvantages which result in an additional burden on the user and an inefficient use of network resources. First, using one template per codec regardless of the frame rate and scene complexity leads to inaccuracies. Second, the user application is required to take steps to determine and transmit appropriate TSpec values, while the TSpec information is often not easily accessible to the user application. Finally, when the user application is unable to access TSpec information, a trial and error method is often employed.
In a manual describing a software program using a so-called token bucket model written by C. Partridge and M. Garrett (1994), a method is described for computing token bucket parameters. For a given r, the system uses a linear pass through the pattern data to determine a large enough b value. However, the algorithm employed ignores the fact that credit growth in the token bucket model may be cut off and does not always give the optimal value for b.
Accordingly, there is a need for a method and apparatus which will automatically and accurately characterize a given traffic pattern while delivering the traffic over a network.
According to an embodiment of the present invention, a method for characterizing network traffic is provided. First, a traffic pattern for said network traffic is recorded at a source device. Then, at least one value characterizing the network traffic is generated.